The complement system can be activated by:
A) the binding of complement protein 1 to the complement-binding site on the antibody molecule.
B) the binding of complement protein 3 to bacteria or viruses in the presence of properdin.
C) nonspecific immune mechanisms.
D) all of the above.

Question

Quizplus · Accepted Answer

The complement system can be activated by several mechanisms. These include the binding of complement protein 1 to the complement-binding site on the antibody molecule (classical pathway), the binding of complement protein 3 to bacteria or viruses in the presence of properdin (alternative pathway), and nonspecific immune mechanisms (lectin pathway). Therefore, the best choice is D, as all of the above mechanisms can activate the complement system.

The Complement System Can Be Activated By